Non Invasive Measurement of Systolic Blood Pressure in Rats: A Simple Technique

Abstract

Background: Non invasive, simple and economical instrument to measure blood pressure in r365-ats is important in cardiovascular research. Methods: Systolic blood pressure measuring instrument was fabricated using a tail cuff, photoplethysmograph, pressure transducer and PC with Biopac Software for recording. Tail cuff was used to occlude the tail artery, photoplethysmograph picked the blood flow pulses in the rat tail and the pressure transducer measured the cuff pressure and converted it into analog voltage. PPG signals were converted into voltage and amplified by the recording system with two channel amplifiers and in addition it also amplified analog voltage converted by the pressure transducer. Results: Calibration of the instrument entailed a simple Bland Altman’s plot of pressure recorded as voltage changes against pressure changes in the mercury sphygmomanometer which is considered as gold standard. A regression value of r=0.9 and p=0.00 was obtained. A pilot study was done on ten female rats. Three blood pressure readings were taken on two occasions. Between - animal variation of BP was 123±7 (mean SD), CV=5.9% and within - animal variation of BP was 120 ±7, CV=5.5%. Conclusion: The tail cuff and PPG based technique to measure systolic blood pressure in rats is simple, economic, accurate and reliable.

Keywords

• tail cuff
• blood pressure
• photoplethysmograph (PPG)